<div id="test">
    <ul>
        <li v-repeat="items" v-class="'list-' + $index">
            <ul>
                <li v-repeat="items" v-class="'list-' + $index">
                    {{$parent.$index + '.' + $index + ' : ' + $parent.title + '&lt;-' + title}}
                </li>
            </ul>
        </li>
    </ul>
    <button id="b0" v-on="click: items[0].title = 'hi'">1</button>
    <button id="b1" v-on="click: items[1].title = 'hi'">2</button>
    <button id="b0-0" v-on="click: items[0].items[0].title = 'hi'">1.1</button>
    <button id="b0-1" v-on="click: items[0].items[1].title = 'hi'">1.2</button>
    <button id="b1-0" v-on="click: items[1].items[0].title = 'hi'">2.1</button>
    <button id="b1-1" v-on="click: items[1].items[1].title = 'hi'">2.2</button>
</div>

<script src="../../../dist/vue.js"></script>
<script>
Vue.config({debug:true})
var items = [
    { title: 0, items: [{title:0}, {title:1}] },
    { title: 1, items: [{title:0}, {title:1}] }
]
new Vue({
    el: '#test',
    data: {
        items: items
    }
})
</script>